The Technical Definition: The right rear wheel speed sensor reading is different from the readings received from the other sensors at a vehicle speed above 25 mph.

Common Symptoms: The ABS or traction control light will illuminate on the dash, the speedometer may read erratically, and the traction control system becomes disabled.

Typical Fix: The fix usually involves replacing the right rear wheel speed sensor, repairing damaged wiring, or addressing a damaged or rusted tone ring.